How to easily write a multi-line file with variables (python 2.6)?

Question

At the moment I'm writing a multi-line file from a python program by doing

myfile = open('out.txt','w')
myfile.write('1st header line\nSecond header line\n')
myfile.write('There are {0:5.2f} people in {1} rooms\n'.format(npeople,nrooms))
myfile.write('and the {2} is {3}\n'.format('ratio','large'))
myfile.close()

This is a bit tiresome and subject to typing errors. What I would like to be able to do is something like

myfile = open('out.txt','w')
myfile.write(
1st header line
Second header line
There are {npeople} people in {nrooms} rooms
and the {'ratio'} is {'large'}'
myfile.close()

Is there any way of doing the something like this within python? A trick could be to write it out to a file and then use sed targeted replacement, but is there an easier way?

Is `npeople` really a float or be output as a float respectively? I am asking because of the `{0:5.2f}` format specifier. — cyroxx, Apr 23 '13 at 06:49

bruno desthuilliers · Accepted Answer · 2013-04-23T08:04:15.747

33

Triple-quoted strings are your friend:

template = """1st header line
second header line
There are {npeople:5.2f} people in {nrooms} rooms
and the {ratio} is {large}
""" 
context = {
 "npeople":npeople, 
 "nrooms":nrooms,
 "ratio": ratio,
 "large" : large
 } 
with  open('out.txt','w') as myfile:
    myfile.write(template.format(**context))

edited Apr 23 '13 at 08:04

answered Apr 23 '13 at 06:38

bruno desthuilliers

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Nice clean solution. One thing: What about the `{0:5.2f}` format specifier? – cyroxx Apr 23 '13 at 07:15
Thanks, that's very helpful. It's just missing my 5.2f format specifier - Otherwise it seems perfect. – Tetsuo Apr 23 '13 at 07:16
Very nice. Thank you very much! – Tetsuo Apr 23 '13 at 10:23

How to easily write a multi-line file with variables (python 2.6)?

1 Answers1